Let's do some clarifying here.
All Mac OS X 10.5 retail disks, including the ones that come with all new Macs, are compatible with both PowerPC and Intel; they're Universal. Now, the DVDs DO however have checks on them to make sure you're installing them on the hardware that they came with, but these can easily be bypassed with a few tweaks.
QUOTE(dillon31292 @ Aug 7 2008, 10:27 PM)

While we're at it though, will OSx86 disks work on a PPC?
OSx86 disks will not work on a PPC, they're specially made for PCs and nothing else.